diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 3ba3f77..f44a30d 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -6498,8 +6498,9 @@
 
     switch (flags) {
         case AUDIO_INPUT_FLAG_NONE:
-        case AUDIO_INPUT_FLAG_FAST: // just fast, not fast|raw || fast|mmap
             break;
+        case AUDIO_INPUT_FLAG_FAST: // disallow hifi record for FAST as
+                                    // it affects RTD numbers over USB
         default:
             return !allowed;
     }